On a 25 questions Math test, Peter got 60% of the 10 algebra questions correct, 80% of the 10 geometry questions correct and 60% of the 5 trigonometry questions correct. What percentage of all the questions did Peter get correct

Solution

60% of the 10 algebra questions correct

60% * 10 = 6

80% of the 10 geometry questions correct

80% * 10 = 8

60% of the 5 trigonometry questions correct

60% * 5 = 3

Total number of questions

6 + 8 + 3 = 17

Percentage of correct questions

17 / 25 = 0.68 = 68%

If 25% of y is x, then y =

Solution

"25% of y is x" is mathematically translated as

(25 / 100) y = x

Solve for y

25 y = 100 x

y = (100 x) / 25

y = 4x

What fraction subtracted from 1/2 + 4/5 gives 1?

Solution

Let x be the fraction to be subtracted. Hence

(1/2 + 4/5) - x = 1

Solve for x

x = (1/2 + 4/5) - 1

x = (5/10 + 8/10) - 10/10 = 3/10

One out of 5 of a group of students took a math test, 28% of the same group took a science test and the rest took a history test. What percent of students took a history test?

Solution

One out of 5 may be written as a fraction equal to

1/5

and in percent as

20%

So 20% took math and 28% took science. The percent of those who took history is